A wide variety of capsules are known including gelatin capsules such as soft capsules prepared by adding glycerin to gelatin, gelatin hard capsules which are essentially composed of gelatin and do not contain glycerin, cellulose-based hard capsules which are essentially composed of a cellulose derivative substrate, and the like. Hard capsules are commonly used in the pharmaceutical and health food fields. Of the hard capsules, gelatin capsules are most widely used. They are formed from a film of a composition comprising gelatin as a base, and other elements including opacifying agent, colorant agent, pigment, and other additives. Typically, gelatin capsules are manufactured by dipping pins in an aqueous gelatin solution having the above components blended, drawing out the pins with the aqueous gelatin solution adhering to the pins, and drying the gelatin coats.
Such capsules include various colorants to provide a color of the capsule and printing on the capsule resulting from edible inks imprinted on the surface of the capsule.
A capsule according to the invention will have a shelf life of no less than sixty months, which may be the future expiry date of capsules. In this case, shelf life may be determined as regards the stability of the shell when monitoring attributes of the capsule including moisture content, weight, brittleness, and overall physical appearance of the capsule. These attributes will be stable for empty hard gelatin capsules stored in a properly sealed container at the manufacturer's stated storage conditions. For example, for a capsule having a shelf life of at least sixty months, the shell of the capsule will not fail storage stability tests due to weight variation for a storage period of at least sixty months.
Such capsules may include an active biological ingredient such as pharmaceuticals, and hence, be subject to FDA testing and approval. Testing of such capsules often requires a 3 month accelerated condition storage testing of the capsule filled with active biological ingredient(s) and any excipient(s) for evaluation of any issues related to interaction of the capsule components, colorants or edible inks with the filled materials. The completion of this testing may take over 6 months.
To achieve testing with the assurance that the colorant and edible ink utilized for the capsules encompasses the commercial trade dress, this testing is typically completed after color and print selection. The color and print selection process and subsequent custom capsule manufacturing process may require 6 months or more prior to completion, which results in a 6 month delay in the approval of the pharmaceutical capsule. Any delay in the approval process is costly and unwanted. Discoloration of the shell would be considered a minor issue and there is no extended benefit from this product in that regard. The major focus of stability studies is potency and availability of the active ingredient. The customer's main concern related to capsules during their stability evaluation is that the capsule ingredients do not interact with their fill material causing an issue with potency or availability.
The present invention is directed to a capsule, which includes a mixture of colorants, which provides color of the capsule within an acceptable range for FDA testing purposes.